This invention relates to connections adapted to engage with a pintle hook tow point of the kind used for towing trailers and the like.
Pintle hook tow points are used for connections between vehicles and trailers mainly in heavy duty and off road applications. A large user of pintle hooks are defence forces. Although there are variations between pintle hooks from various manufacturers they share a common mode of operation. Most pintle hooks are characterised by a horn having an upwardly directed end over which a loop or ring on a trailer draw bar is placed. A mechanism is provided to close the open part of the hook so as to provide a captive eyelet for the ring or loop which permits a large degree of relative movement in two planes. Whilst this movement is desirable for trailer towing there are some applications in which movement is not required. One such application arises in connection with devices for collecting debris from a surface of the kind described in International Patent Applications WO96/09440 and WO98/29609 by the present applicant. Devices of this kind are required to be towed across a surface from a towing point positioned close to the surface over which the vehicle is driven. This is achieved by providing a tow hitch that depends downwardly from the towing point of the vehicle used to tow the collecting device. In the case of most tow points it is possible to establish a connection between the towing point which does not provide for any substantial movement. The risk of the depending hitch striking an obstruction or the ground due to unevenness in the surface is accommodated by providing a spring loaded mechanism within the hitch device itself. A difficulty arises however when it is desired to connect this type of depending tow hitch to a vehicle fitted with a pintle hook towing point. This can be a particular difficulty because the debris collection devices are adapted for collection of fine objects from airport surfaces. Many airports are maintained by defence forces which have vehicles provided with a pintle hook tow point.
It is an object of this invention to provide a connection for a pintle hook tow point that will provide a substantially rigid mounting point with respect to the vehicle.
Accordingly, in one aspect this invention provides a connection for a pintle hook tow point of a vehicle comprising a transverse member for engagement with the horn of the pintle hook tow point, a bracket mounting said transverse member and extending for engagement with a surface which is in use of the connection fixed with respect to the vehicle, and selectively operable locking means for acting between the said engagement and said transverse member to clamp the connection between the fixed surface and an inner rear surface of the horn.
The fixed surface may comprise, for example, a surface on the vehicle, such as a rear surface, a mounting plate or other mounting of the pintle hook tow point, or one or more surfaces on fixing elements for attaching the pintle hook tow point to the vehicle.
Preferably, the bracket includes spaced apart protuberances to respectively engage lateral sides of the pintle hook tow point or latch to further stabilise the connection. In the preferred form these protuberances can be made adjustable, for example by taking the form of threaded bolts with lock nut arrangements.
The transverse member is preferably a cylindrical element. A groove or depression is preferably formed in the central region of the transverse member so as to provide for a more stable engagement with the inner rear surface of the horn. In an alternative configuration a resiliently deformable material can be used for the cylindrical element so that it at least partially conforms to the shape of the inner rear surface of the horn under load.
The selectively operable locking means is preferably formed by the transverse member being eccentrically mounted on an axle. An arm, or pair of arms can be used to rotate the eccentrically mounted transverse member so as to increase the distance between the surface of the member bearing against the inner surface of the horn and the extension of the bracket bearing against the vehicle or pintle hitch mounting plate. The arm or arms are preferably provided with means to lock them in an engaged position. This is preferably achieved by providing an appropriate stop on the bracket against which the arms bear and an aperture through which a locking pin or the like can be inserted.
In order to provide for use of the connection with a wide range of pintle tow points the transverse member is preferably mounted for movement with respect to a slotted aperture within the bracket so as to allow a coarse adjustment of the distance between the member and the surface of the bracket which in use bears against said fixed surface. The bracket is preferably of a generally U-shaped form with an open end for bearing against the fixed surface and a closed end for fitting behind the horn. A connection point for the attachment point for the article to be used with the connection is preferably formed by a rearward extension from the closed end. The transverse member thus extends between and is mounted through two arms of the U-shaped bracket.
It will be apparent that the connection for a pintle tow point of this invention thus provides a substantially rigid mounting for implements such as the tow hitch associated with the applicant""s foreign object debris collection device. The connection is adjustable to accommodate variations between different types of pintle hook tow points and can be simply and quickly installed and removed from the pintle hook tow point.